The latest news from mBio, a new online, open-access journal from the American Society for Microbiology.

January 2013

01/29/2013

Iron oxidizing bacteria aren’t exactly rare, but they’re hard to study in the lab because of the copious amounts of oxidized iron (Fe(III)) they produce. In mBio this week, a group at the University of Minnesota – Twin Cities describes a new method for growing iron-oxidizing bacteria

Reactor for growing iron oxidizers. No orange slime in sight...

using a steady flow of electrons, an advance that will allow them to better study the organisms. It also opens the possibility that one day electricity generated from renewable sources like wind or solar could be funneled to iron oxidizing bacteria that combine it with carbon dioxide to create biofuels, capturing the energy as a useful, storable substance.

“It’s a new way to cultivate a microorganism that’s been very difficult to study. But the fact that these organisms can synthesize everything they need using only electricity makes us very interested in their abilities,” says Daniel Bond of the BioTechnology Institute at the University of Minnesota – Twin Cities, who co-authored the paper with Zarath Summers and Jeffrey Gralnick.

To respire, iron oxidizers take electrons off of dissolved iron, called Fe(II) – a process that produces copious amounts of rust, called Fe(III). Iron oxidizing bacteria are found around the world, almost anywhere the aerobic environment meets an anaerobic environment. They play a big role in the global cycling of iron and contribute to the corrosion of steel pipelines, bridges, piers, and ships, but their lifestyle at the interface of two very different habitats and the accumulation of cell-trapping Fe(III) makes iron oxidizers difficult to grow and study in the lab.

An electrode or “the world’s best buffet of iron atoms”?

Bond says the prevailing theory is that iron oxidizers must carry out the oxidation step on the surface of the cell. If that’s true, Bond reasoned, the outsides of the organisms should be covered with proteins that interact with Fe(II), so you should be able to provide a stream of pure electrons to the outsides of the bacteria and get them to grow.

Bond and his colleagues added the marine iron oxidizer Mariprofundus ferrooxydans PV-1, along

with some nutrient medium, to an electrode carefully tuned to provide electrons at the same energy level, or potential, as Fe(II) would provide. The idea, says Bond, was to “fool the bacteria into thinking they’re at the world’s best buffet of Fe(II) atoms.”

It worked. The bacteria multiplied and formed a film on the electrode, Bond says, and eventually they were able to grow M.ferrooxydans with no iron in the medium, proof that the bacteria were living off the electrons they absorbed from the electrode to capture carbon dioxide and replicate. And since the electron donor is a solid surface, say the authors, it’s pretty likely that the bacterial electron-harvesting machinery is exposed on the outer membrane of the cell.

A future in energy storage

It’s this capture of carbon dioxide that could enable electrochemical cultivation to create biofuels or other useful products one day, Bond says.

“Bacteria are experts at the capture of carbon dioxide. They build cells and compounds” with the carbon, he says. They might one day be exploited as microscopic energy packagers: bacteria like M. ferrooxydans could capture electricity from an electrode, combine it with carbon dioxide, and package it as a carbon-rich compound we could use as fuel. This would take the energy in electricity, which is ephemeral, and convert it into a tangible product that could be stored in a tank. But that kind of work is a long way off, cautions Bond.

“If there are 100 steps to making this work – this is step one,” he says.

01/22/2013

It’s not hard to see that men are more likely to engage in risky behaviors than women, or that crime rates are many times higher among men, but this tendency to break the rules also extends to male scientists, according to a study in mBio this week. An analysis of data from the Office of Research Integrity reveals that men commit research misconduct more often than their female peers, a gender disparity that is most pronounced among senior scientists.

In their study in mBio, co-authors Ferric C. Fang of the University of Washington School of Medicine in Seattle, Joan W. Bennett of Rutgers, and Arturo Casadevall of Albert Einstein College of Medicine, scrutinized data from the U.S. Office of Research Integrity, an organization that investigates allegations of misconduct in research supported by the Department of Health and Human Services. “Misconduct” includes such infractions as fabrication, falsification or plagiarism.

The numbers revealed that out of the 227 individuals sanctioned for committing scientific misconduct between 1994 and the present, 66% were male, a number that far outstrips their overall representation among researchers in the life sciences. And although men represent about 70% of faculty in the life sciences, 88% of faculty who committed misconduct were male.

“Not only are men committing more research misconduct,” says Bennett, “senior men are most likely to do so.”

Senior scientists responsible for 60% of misconduct

Gender distribution of scientists committing misconduct.

If the fact that men are more likely to commit scientific misconduct is less than surprising, Casadevall says, what did surprise the authors is the fact that misconduct is not confined to inexperienced, early-career strivers.

“When you look at the numbers, you see that the problem of misconduct carries through the entire career of scientists,” says Casadevall. Faculty (32%) and other research personnel (28%) represented a total of 60% of cases, whereas students (16%) and post-doctoral fellows (25%) were sanctioned in only 41% of cases.

Casadevall says this disparity belies the common conception that misconduct is most often committed by research trainees striving to make a name for themselves. “Those numbers are very lopsided when you look at faculty. You can imagine people would take these risks when people are going up the ladder,” says Casadevall, but once they’ve made it to the rank of “faculty”, presumably the incentive to get ahead would be outweighed by the risk of losing status and employment, he says. Not so, apparently.

Is misconduct driving women out of research?

Bennett asserts that the “winner take all” reward system of science and pressure to secure funding that drives researchers of both sexes into misconduct is also to blame for driving women out of research. “Many women are totally turned off by the maneuverings and starkly competitive way of the academic workplace,” says Bennett. “Cheating on the system is just one of many factors that induce women to leave academe and seek professional careers in other environments.”

But why do men in the life sciences commit fraud more often than the women they work with? It’s probably a combination of factors, says Fang. “A variety of biological, social and cultural explanations have been proposed for these differences,” he says. “But we can’t really say which of these apply to the specific problem of research misconduct.” Biology can’t be ruled out, but the authors point to recent studies that indicate competitive tendencies arise from social and cultural influences.

Regardless of the reasons why, the fact remains that research misconduct continues, even in the face of mandatory ethics training for research trainees at many institutions. Now that it’s clear the problem of misconduct is not confined to trainees, it may be time to broaden ethics training to include the more senior researchers who seem to be driving the problem.

“Misconduct is a tremendous problem in science,” says Casadevall. “The data show that it’s coming predominantly from one gender. I think as scientists we need to understand it and try to reduce it.”

In December, Muller et al. revealed that the new coronavirus, called HCoV-EMC, does not share the same receptor as SARS. So, what receptor does HCoV-EMC use? The pattern of infection could offer hints, say Perlman and Zhao. Avian H5N1 flu also causes severe infection but limited transmissibility, so the H5N1 receptor, glycans that contain a terminal α2,3-linked sialic acid, may have something in common with the HCoV-EMC receptor. However, if, like SARS, the receptor for HCoV-EMC is a protein, it is probably distributed in the human lung in much the same way as the SARS receptor: localized to the deeper parts of the lung, a location that necessarily limits spread from person to person.

Sialic acid or protein, finding the receptor is imperative, write Perlman and Zhao, not only for disease control, but also for understanding how the virus apparently ropes the renal system into the infection, a unique feature among coronaviruses.

The broad host range of the virus is yet another unique feature, say Perlman and Zhao. How is it that bats can (apparently) carry HCoV-EMC without getting sick? Understanding the bat response to the virus could help us understand the human response and point the direction to drugs and other therapies to diminish the impact of the disease.

Will HCoV-EMC become a global problem? Perlman and Zhao say the future is uncertain. As a first step, diagnosing past and present HCoV-EMC infections is critical for figuring out how common and deadly the virus is. If the virus infects humans only rarely it may not become the major health issue health agencies worry about.

serious and invasive infections, including septic arthritis, impetigo, and necrotizing fasciitis, so a vaccine for group A Strep (GAS) could not only keep Strep-throat-prone kids in school, it could potentially spare a great deal of human suffering.

The study in mBio follows up on earlier work that found the GAS protein streptolysin O was an effective antigen to use in an experimental vaccine in mice. However, streptolysin O is also a really potent toxin, so a vaccine that uses unadulterated streptolysin O could do more harm than good.

To get around this little detail, the group used protein structural predictions (see image) to design a detoxified version of streptolysin O. After identifying the components of streptolysin that might be responsible for its toxic activity – the regions that bind and form pores in human cells – they created a double mutant version of the protein that not only lacks toxicity, it is highly protective in immunizing mice against GAS. So it’s different enough to be safe, but still similar enough to the wild type streptolysin O to train the mouse immune system to attack GAS.

This particular study addressed GAS, but the results can be applied to vaccine development in any number of pathogens, the authors write. It’s also a good approach for studying virulence: researchers can use genetically constructed detoxified virulence factors to dissect the contributions of various functional and structural properties to the ability of a pathogen to establish and maintain infections.